Abstract: A cooling apparatus especially for cooling high-temperature-superconducting lectronic components includes a cold gas cooling machine, such as a Stirling machine, thermally connected to a pressure vessel serving as a cold reservoir vessel. The pressure vessel contains a working medium having a triple point in the temperature range from about 60K to about 90K and a critical temperature at least as high as the maximum operating room temperature of the apparatus. The working medium is propane, for example. A cooling surface of the electronic component is thermally connected to the pressure vessel. In the method of operating the apparatus, the electronic component does not require continuous cooling. During a charging or refrigerating phase, the cooling machine freezes the working medium. Then during a useful cooling phase, the cooling machine is switched off and the electronic component is operated while being cooled by the frozen working medium.